How do I set both StrikeThrough and Underline styling options for text inside a JTextPane?

Question

I have a JTextPane component and I am trying to style the text that will be typed by the user to be both underline and strikethrough at the same time.

The relevant snippet of code that that should set the strikethrough attribute of the next typed character to true is this:

JEditorPane editor = getEditor(e);
if (editor != null) {
     StyledEditorKit kit = getStyledEditorKit(editor);
     MutableAttributeSet attr = kit.getInputAttributes();            
     SimpleAttributeSet sas = new SimpleAttributeSet();
     StyleConstants.setStrikeThrough(sas, true);                
     setCharacterAttributes(editor, sas, false);
}

This does style the text as strikethrough, but if it was already styled as underline, it loses the underline styling information. Taking a close look at the actual code behind StyleConstants.setStrikeThrough(...) I have noticed that the CSS styling tag for both underline and strikethrough attributes will be the same (i.e. "text-decoration") and when the value is updated in the hashtable holding the attributes, it will be overriden.

This means that code like:

StyleConstants.setStrikeThrough(sas, true);
StyleConstants.setUnderlineThrough(sas, true);

will result in the next typed character being underlined without a strikethrough. I've checked the attribute values and for the "text-decoration" attribute the value is "underline", whereas I was expecting "line-through,underline".

Does anyone know how to achieve this in a clean Swing compliant way? Is there something wrong in my approach? Is there an underlying assumption at the core of JTextPane styling that text should not be strikethrough and underline at the same time?

Answer 1

Why not working with StyledDocument and using two Style: primary and secondary, where primary is parent style of secondary:

  StyledDocument styleDocument =  jTextPane1.getStyledDocument();
  Style primaryStyle = styleDocument.addStyle("Primary", null);
  Style secondaryStyle = styleDocument.addStyle("Secondary", primaryStyle);


  StyleConstants.setFontFamily(primaryStyle, "American Captain");
  StyleConstants.setFontSize(primaryStyle, 24);

//  StyleConstants.setFontFamily(secondaryStyle, "Bira PERSONAL USE ONLY");
  StyleConstants.setFontSize(secondaryStyle, 20);
  StyleConstants.setForeground(primaryStyle, new Color(0x552AFF));
  StyleConstants.setForeground(secondaryStyle, Color.black);
  StyleConstants.setStrikeThrough(secondaryStyle, true);
  StyleConstants.setUnderline(primaryStyle, true);

  try {
      styleDocument.insertString(0, "Title with American Captain font\n\n", primaryStyle);
      styleDocument.insertString(styleDocument.getLength(), "Font demonstration with JTextPane. "
              + "Seriously, it is powerful and has the power to do all kind of styling with text. "
              + "check it out, check its mighty power and be embrassed\n", secondaryStyle);
   } catch (BadLocationException ex) {
                Logger.getLogger(JTextPaneTest.class.getName()).log(Level.SEVERE, null, ex);
   }

Edit:

imagine you have 4 toggle buttons - italic, bold, underline and strikethrough. Each time one of those is pressed or unpressed I need to adjust the styling as necessary for the character that will be typed next.

Yes, the answer still lies in the preference of using DefaultStyleDocument and extending it. The above example should give an idea how styling with Style works while inserting string with styleDocument.insertString(int offs, String str, AttributeSet a) method. When we are inserting data using KeyBoard or copy-paste the associating StyleDocument's insertString function always gets called.

So, to style like a text editor as you are wanting, all you have to do is to extends the DefaultStyleDocument and override this insertString function and pass the specific style attribute you want.

A Demo example satisfying your complete requirement should make this things clear.

class CStyleDocument extends DefaultStyledDocument
{
    private  Style primaryStyle;

    public CStyleDocument() {
        super();
         primaryStyle = this.addStyle("Primary", null);
    }
    public Style getAttrStyle()
    {
        return primaryStyle;
    }

    @Override
    public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
        super.insertString(offs, str, primaryStyle); 

    }

}

public class JTextPaneTest extends javax.swing.JFrame {

    CStyleDocument styleDocument;

    public JTextPaneTest() {
        initComponents();

        styleDocument = new CStyleDocument();
        jTextPane1.setDocument(styleDocument);

}

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jScrollPane1 = new javax.swing.JScrollPane();
        jTextPane1 = new javax.swing.JTextPane();
        jPanel1 = new javax.swing.JPanel();
        boldSelButton = new javax.swing.JToggleButton();
        ulSelButton = new javax.swing.JToggleButton();
        strkSelButton = new javax.swing.JToggleButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setMinimumSize(new java.awt.Dimension(400, 200));

        jScrollPane1.setViewportView(jTextPane1);

        getContentPane().add(jScrollPane1, java.awt.BorderLayout.CENTER);

        boldSelButton.setText("Bold");
        boldSelButton.addChangeListener(new javax.swing.event.ChangeListener() {
            public void stateChanged(javax.swing.event.ChangeEvent evt) {
                boldSelButtonStateChanged(evt);
            }
        });
        jPanel1.add(boldSelButton);

        ulSelButton.setText("Under Lined");
        ulSelButton.addChangeListener(new javax.swing.event.ChangeListener() {
            public void stateChanged(javax.swing.event.ChangeEvent evt) {
                ulSelButtonStateChanged(evt);
            }
        });
        jPanel1.add(ulSelButton);

        strkSelButton.setText("Strike Through");
        strkSelButton.addChangeListener(new javax.swing.event.ChangeListener() {
            public void stateChanged(javax.swing.event.ChangeEvent evt) {
                strkSelButtonStateChanged(evt);
            }
        });
        jPanel1.add(strkSelButton);

        getContentPane().add(jPanel1, java.awt.BorderLayout.PAGE_START);

        pack();
    }// </editor-fold>                        

    private void boldSelButtonStateChanged(javax.swing.event.ChangeEvent evt) {                                           
             StyleConstants.setBold(styleDocument.getAttrStyle(), ((JToggleButton)evt.getSource()).isSelected());
             jTextPane1.requestFocus();




    }                                          

    private void ulSelButtonStateChanged(javax.swing.event.ChangeEvent evt) {                                         
        StyleConstants.setUnderline(styleDocument.getAttrStyle(), ((JToggleButton)evt.getSource()).isSelected());
        jTextPane1.requestFocus();
    }                                        

    private void strkSelButtonStateChanged(javax.swing.event.ChangeEvent evt) {                                           
       StyleConstants.setStrikeThrough(styleDocument.getAttrStyle(), ((JToggleButton)evt.getSource()).isSelected());
       jTextPane1.requestFocus();
    }                                          


    public static void main(String args[]) {

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new JTextPaneTest();
                frame.setVisible(true);

            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JToggleButton boldSelButton;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextPane jTextPane1;
    private javax.swing.JToggleButton strkSelButton;
    private javax.swing.JToggleButton ulSelButton;
    // End of variables declaration                   
}